[Objective]To investigate the effects of lysophosphatidic acid(LPA) on the morphology,proliferation and brain-derived neurotropic factor(BDNF) expression of olfactory ensheathing cells(OECs) in vitro.[Method]Primary cultures of OECs separated from adult rat olfactory bulbs were purified and cultured.Five experimental cultures were grown for a period of time in media with LPA at different concentrations,namely 1,5,10,20 and 50 ?mol/L,and the control culture was grown in the medium without LPA.Immunofluorescent staining was used to identify OECs and to observe their morphological changes.The proliferation of OECs was measured by MTT assay.Western blotting was used to detect the protein expression of BDNF.[Result]Exposure to LPA in medium induced the switch in the dominant morphology of OECs from process-bearing to flat morphology.This shift in morphology was reversed when LPA was removed from media.LPA at concentrations from 1 ?mol/L to 50 ?mol/L enhanced OECs proliferation,especially at the concentration of 10 ?m/L.Proliferation of OECs in all experimental cultures reached their respective significant peaks after 60 h of LPA treatment.There were significant upregulations in BDNF expression of OECs treated with LPA(1~50 ?m/L) compared with those in the control culture.[Conclusion]A reversible change from process-bearing to flat in morphology of OECs can be induced by LPA.LPA stimulates OECs proliferation in a time-and concentration-dependent manner.LPA upregulates BDNF expression of OECs.